1. Field of the Invention
The present invention relates to a manganese oxide material having MnO.sub.3 as a matrix, that exhibits light-induced insulator-to-metal transition and the accompanying antiferromagnetic-to-ferromagnetic transition and can advantageously be used as a switching device or memory device.
2. Description of the Prior Art
The discovery of high-temperature superconductivity in copper oxides has drawn attention to the spin-charge coupled dynamics of oxides of transition metals. One on which research is being conducted is perovskite type manganese oxide materials that exhibit negative colossal magnetoresistance (CMR).
While there are known many perovskite type oxide materials that exhibit the CMR effect such as for example Pr.sub.1-x Ca.sub.x MnO.sub.3, Pr.sub.1-x (Ca.sub.1, Sr).sub.x MnO.sub.3 and Nd.sub.0.5 Sr.sub.0.5 MnO.sub.3 (Physical Review Letters, vol. 71, page 2331: Applied Physics Letters, vol. 63, page 1990; Science, vol. 264, page 413), in each of these materials the negative CMR effect is insulator-to-metal phase transition induced by application of an external magnetic field. Thus, even when switching or memory devices are formed using such materials, application to electronics-related fields has been difficult.
An object of the present invention is to provide a manganese oxide material exhibiting insulator-to-metal transitions that can be controlled by light.